Osteoarthritis, KneeNCT07514598
Effect of J-Shaped Incision After Total Knee Arthroplasty (J-TKA)
A study testing Conventional Midline Incision and J-shaped Incision in people with Osteoarthritis, Knee, run by Fatih Sultan Mehmet Training and Research Hospital at 1 site in Turkey (Türkiye).
Trial summary
This prospective randomized controlled trial evaluates whether a modified J-shaped skin incision can reduce peri-incisional numbness after primary total knee arthroplasty (TKA) compared with the conventional midline skin incision. Read more about this study
- Who is it for?
- Ages 56 to 81 years
- Conditions the study is for
- Osteoarthritis, Knee
- What is being tested?
- Conventional Midline Incision and J-shaped Incision
- Type of treatment
- Surgery or procedure
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 62 participants
- Where
- 1 siteTurkey (Türkiye)
- Study dates
- 17 Sep 2025to 17 May 2026
- Phase
- Interventional
- Are there results?
- None posted in the registry
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 56 to 81 years
- All sexes
- No healthy volunteers
- Adult, Older adult
Who may be able to join
- Adults undergoing primary total knee arthroplasty
- Diagnosis of Kellgren-Lawrence grade 4 varus knee osteoarthritis
- Planned treatment with primary total knee arthroplasty
- Ability to provide written informed consent
- Ability to comply with postoperative follow-up evaluations
Who cannot join
- Valgus knee deformity
- Revision total knee arthroplasty
- Previous surgery on the affected knee
- History of periarticular fracture around the knee
- Pre-existing sensory deficit or neurologic disorder affecting the operative lower extremity
- History of lumbar disc herniation
Show all 10Show fewer
- Known neuromuscular disease
- Peripheral vascular disease
- Inability to comply with follow-up and postoperative evaluations
- Refusal or inability to provide informed consent
Trial locations and contacts
1 site in 1 country.
Turkey (Türkiye)1 site
Fatih Sultan Mehmet Training and Research Hospital
Ataşehir, Istanbul, 34752
About this study
Official title: J-Shaped Incision Reduces Peri-incisional Numbness and Pain After Primary Total Knee Arthroplasty: A Prospective Randomized Controlled Trial
This prospective randomized controlled trial evaluates whether a modified J-shaped skin incision can reduce peri-incisional numbness after primary total knee arthroplasty (TKA) compared with the conventional midline skin incision. Peri-incisional numbness is a common postoperative complaint after TKA and is thought to be mainly related to injury of the infrapatellar branch of the saphenous nerve. Although often considered a minor issue, it may adversely affect postoperative comfort, pain perception, and patient satisfaction.
A total of 62 patients undergoing primary TKA for Kellgren-Lawrence grade 4 varus knee osteoarthritis were randomized to either a conventional midline incision or a modified J-shaped incision. In the J-shaped technique, the distal part of the incision is curved laterally at the level of the tibial tuberosity in an effort to decrease injury to the infrapatellar branch of the saphenous nerve. The primary outcome is the extent of peri-incisional sensory loss, assessed using Semmes-Weinstein 10-g monofilament testing with a grid-mapping method before surgery and at 2 and 6 months after surgery. Secondary outcomes include pain scores, functional knee scores, range of motion, blood loss, tourniquet time, and wound-related complications.
Read the detailed description
Total knee arthroplasty is an effective surgical treatment for advanced knee osteoarthritis; however, peri-incisional numbness is a frequent postoperative finding. This sensory disturbance is commonly attributed to injury of the infrapatellar branch of the saphenous nerve during the standard anterior skin incision. Although peri-incisional numbness is often not regarded as a major complication, it may negatively influence postoperative comfort and patient satisfaction and may also be associated with persistent local pain.
This study was designed to investigate whether a modified J-shaped skin incision could reduce peri-incisional numbness compared with the conventional midline incision in patients undergoing primary TKA. The underlying rationale is that altering the distal course of the skin incision laterally near the tibial tuberosity may help decrease injury to the infrapatellar branch of the saphenous nerve while preserving standard surgical exposure and not increasing operative difficulty or wound-related complications.
In this prospective randomized controlled trial, 62 patients with Kellgren-Lawrence grade 4 varus osteoarthritis scheduled for primary TKA were allocated to one of two groups: a conventional midline incision group or a modified J-shaped incision group. In the modified technique, the distal portion of the incision is curved laterally by approximately 3 cm at the level of the tibial tuberosity. All participants undergo peri-incisional sensory evaluation preoperatively and again at 2 and 6 months postoperatively. Sensory loss is quantified using Semmes-Weinstein 10-g monofilament testing combined with a grid-mapping method to determine the area of numbness.
The primary outcome measure is the area of peri-incisional numbness after surgery. Secondary outcome measures include postoperative pain assessed by visual analog scale (VAS), functional outcomes assessed by The Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), Knee Injury and Osteoarthritis Outcome Score (KOOS), Hospital for Special Surgery Knee-Rating Scale (HSS) and Anterior Knee Pain Scale (AKPS) scores, range of motion, estimated blood loss, tourniquet time, and wound-related complications. These measures are intended to determine whether the modified incision provides sensory and pain-related benefits without adversely affecting clinical recovery, surgical efficiency, or wound healing.
Based on the study findings summarized in the abstract, the modified J-shaped incision was associated with a significantly smaller area of postoperative numbness at both 2 and 6 months and with lower pain scores at 6 months, while functional scores, range of motion, blood loss, tourniquet time, and wound-related complications were similar between groups. These findings support the hypothesis that a simple modification of the skin incision may improve postoperative sensory outcomes and comfort after primary TKA without increasing surgical risk.
- Conditions
- Osteoarthritis, Knee
- Being tested
- Conventional Midline Incision, J-shaped Incision
- Keywords
- Total Knee Arthroplasty, Knee Osteoarthritis, J-shaped Incision, Saphenous Nerve, Numbness
- Medical subject headings
- Osteoarthritis, Knee, Hypesthesia
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Conventional Midline IncisionProcedure or surgery
Also called Standard midline incision
A conventional midline skin incision is used during primary total knee arthroplasty.
J-shaped IncisionProcedure or surgery
Also called Modified J-shaped incision
A modified J-shaped skin incision is used during primary total knee arthroplasty, in which the distal portion of the incision is curved laterally at the level of the tibial tuberosity.
| Study group | Role | What they receive |
|---|---|---|
| Midline Incision | Active comparator | Participants undergo primary total knee arthroplasty using a conventional midline skin incision. Receives: Procedure: Conventional Midline Incision |
| J-shaped Incision | Experimental | Participants undergo primary total knee arthroplasty using a modified J-shaped skin incision, in which the distal portion of the incision is curved laterally at the level of the tibial tuberosity. Receives: Procedure: J-shaped Incision |
What is being measured
The primary outcome is the main question the study is designed to answer.
Area of peri-incisional sensory loss
The extent of peri-incisional sensory loss will be assessed using Semmes-Weinstein 10-g monofilament testing combined with a standardized grid-mapping method to quantify the area of numbness around the surgical incision.
Measured: 2 months and 6 months postoperatively
Secondary outcomes (10)
Postoperative pain
Postoperative pain will be assessed using the Visual Analog Scale (VAS) for pain at 2 months and 6 months postoperatively. The VAS ranges from 0 to 10, where 0 indicates no pain and 10 indicates the worst imaginable pain. Higher scores indicate worse pain.
Measured: 2 months and 6 months postoperatively
Range of motion
Knee range of motion will be measured clinically in degrees.
Measured: 2 months and 6 months postoperatively
Intraoperative Blood Loss
Intraoperative blood loss will be recorded during the surgical procedure. Blood loss will be measured in milliliters (mL). Higher values indicate greater blood loss.
Measured: Intraoperative period
Tourniquet Time
Tourniquet time will be recorded during the surgical procedure. Tourniquet time will be measured in minutes. Higher values indicate longer tourniquet use.
Measured: Intraoperative period
Incision Length
Incision length will be measured intraoperatively in centimeters (cm). Higher values indicate a longer skin incision.
Measured: Intraoperative period
Wound complications
Postoperative wound-related complications will be assessed clinically.
Measured: Up to 6 months postoperatively
Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) Score
Functional outcome will be assessed using the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) at 2 months and 6 months postoperatively. If reported on a 0 to 100 scale, 0 indicates the worst symptoms/function and 100 indicates the best symptoms/function. Higher scores indicate better outcome.
Measured: 2 months and 6 months postoperatively
Knee injury and Osteoarthritis Outcome Score (KOOS)
Functional outcome will be assessed using the Knee injury and Osteoarthritis Outcome Score (KOOS) at 2 months and 6 months postoperatively. KOOS subscale scores range from 0 to 100, where 0 indicates extreme knee problems and 100 indicates no knee problems. Higher scores indicate better outcome.
Measured: 2 months and 6 months postoperatively
Hospital for Special Surgery (HSS) Knee Score
Functional outcome will be assessed using the Hospital for Special Surgery Knee Score (HSS) at 2 months and 6 months postoperatively. The HSS score ranges from 0 to 100, with higher scores indicating better knee function.
Measured: 2 months and 6 months postoperatively
Kujala Anterior Knee Pain Scale Score
Functional outcome will be assessed using the Kujala Anterior Knee Pain Scale at 2 months and 6 months postoperatively. The score ranges from 0 to 100, with higher scores indicating better knee function and fewer symptoms.
Measured: 2 months and 6 months postoperatively
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted7 Apr 2026
- Study start17 Sep 2025
- Primary completion17 Apr 2026
- Study completion17 May 2026
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Publications (3)Papers the sponsor has linked to this study.
- Other trials for Osteoarthritis, KneeStudies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase N/A
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Model description
- This is a prospective, randomized, parallel-group study comparing a conventional midline incision with a modified J-shaped incision in patients undergoing primary total knee arthroplasty.
- Masking
- None (open label)
- Enrolment
- 62 participants (actual)
Sponsor and investigators
- Lead sponsor
- Fatih Sultan Mehmet Training and Research Hospital
- Sponsor type
- University, hospital or other
- Responsible party
- Principal investigator, Olcay Yavuz, Fatih Sultan Mehmet Training and Research Hospital
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07514598
- Sponsor's protocol ID
- J-TKA-2026
- Status last verified
- May 2026
- First submitted
- 27 Mar 2026
- Last updated
- 29 May 2026
- Results posted
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- No
Publications
James NF, Kumar AR, Wilke BK, Shi GG. Incidence of Encountering the Infrapatellar Nerve Branch of the Saphenous Nerve During a Midline Approach for Total Knee Arthroplasty. J Am Acad Orthop Surg Glob Res Rev. 2019 Dec 12;3(12):e19.00160. doi: 10.5435/JAAOSGlobal-D-19-00160. eCollection 2019 Dec.
PubMed 32072122MacDonald B, Kurdin A, Somerville L, Ross D, MacDonald S, Lanting B. The Effect of Sensory Deficit After Total Knee Arthroplasty on Patient Satisfaction and Kneeling Ability. Arthroplast Today. 2021 Jan 11;7:264-267.e2. doi: 10.1016/j.artd.2020.11.020. eCollection 2021 Feb.
PubMed 33786352Kahraman HC, Kilinc BE, Yavuz O, Erdem HF, Yilmaz B. The effect of J-shaped incision versus standard midline incision on numbness and pain in primary total knee arthroplasty: a prospective randomized controlled trial. Int Orthop. 2026 Jun 26. doi: 10.1007/s00264-026-06918-9. Online ahead of print.
PubMed 42360437
Study at a glance
From the registry record, last updated by the sponsor on 29 May 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- J-Shaped Incision Reduces Peri-incisional Numbness and Pain After Primary Total Knee Arthroplasty: A Prospective Randomized Controlled Trial
- ClinicalTrials.gov ID
- NCT07514598
- Acronym / sponsor ID
- J-TKA-2026
- Conditions
- Osteoarthritis, Knee
- Keywords
- Total Knee Arthroplasty, Knee Osteoarthritis, J-shaped Incision, Saphenous Nerve, Numbness
- Study type
- Interventional
- Recruitment status
- Completed
- Enrolment
- 62 participants (actual)
- Lead sponsor
- Fatih Sultan Mehmet Training and Research HospitalUniversity, hospital or other
- Study start
- 17 Sep 2025 (actual)
- Primary completion
- 17 Apr 2026 (actual)
- Study completion
- 17 May 2026 (actual)
- First posted
- 7 Apr 2026 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
This prospective randomized controlled trial evaluates whether a modified J-shaped skin incision can reduce peri-incisional numbness after primary total knee arthroplasty (TKA) compared with the conventional midline skin incision. Peri-incisional numbness is a common postoperative complaint after TKA and is thought to be mainly related to injury of the infrapatellar branch of the saphenous nerve. Although often considered a minor issue, it may adversely affect postoperative comfort, pain perception, and patient satisfaction.
A total of 62 patients undergoing primary TKA for Kellgren-Lawrence grade 4 varus knee osteoarthritis were randomized to either a conventional midline incision or a modified J-shaped incision. In the J-shaped technique, the distal part of the incision is curved laterally at the level of the tibial tuberosity in an effort to decrease injury to the infrapatellar branch of the saphenous nerve. The primary outcome is the extent of peri-incisional sensory loss, assessed using Semmes-Weinstein 10-g monofilament testing with a grid-mapping method before surgery and at 2 and 6 months after surgery. Secondary outcomes include pain scores, functional knee scores, range of motion, blood loss, tourniquet time, and wound-related complications.
Detailed description
Total knee arthroplasty is an effective surgical treatment for advanced knee osteoarthritis; however, peri-incisional numbness is a frequent postoperative finding. This sensory disturbance is commonly attributed to injury of the infrapatellar branch of the saphenous nerve during the standard anterior skin incision. Although peri-incisional numbness is often not regarded as a major complication, it may negatively influence postoperative comfort and patient satisfaction and may also be associated with persistent local pain.
This study was designed to investigate whether a modified J-shaped skin incision could reduce peri-incisional numbness compared with the conventional midline incision in patients undergoing primary TKA. The underlying rationale is that altering the distal course of the skin incision laterally near the tibial tuberosity may help decrease injury to the infrapatellar branch of the saphenous nerve while preserving standard surgical exposure and not increasing operative difficulty or wound-related complications.
In this prospective randomized controlled trial, 62 patients with Kellgren-Lawrence grade 4 varus osteoarthritis scheduled for primary TKA were allocated to one of two groups: a conventional midline incision group or a modified J-shaped incision group. In the modified technique, the distal portion of the incision is curved laterally by approximately 3 cm at the level of the tibial tuberosity. All participants undergo peri-incisional sensory evaluation preoperatively and again at 2 and 6 months postoperatively. Sensory loss is quantified using Semmes-Weinstein 10-g monofilament testing combined with a grid-mapping method to determine the area of numbness.
The primary outcome measure is the area of peri-incisional numbness after surgery. Secondary outcome measures include postoperative pain assessed by visual analog scale (VAS), functional outcomes assessed by The Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), Knee Injury and Osteoarthritis Outcome Score (KOOS), Hospital for Special Surgery Knee-Rating Scale (HSS) and Anterior Knee Pain Scale (AKPS) scores, range of motion, estimated blood loss, tourniquet time, and wound-related complications. These measures are intended to determine whether the modified incision provides sensory and pain-related benefits without adversely affecting clinical recovery, surgical efficiency, or wound healing.
Based on the study findings summarized in the abstract, the modified J-shaped incision was associated with a significantly smaller area of postoperative numbness at both 2 and 6 months and with lower pain scores at 6 months, while functional scores, range of motion, blood loss, tourniquet time, and wound-related complications were similar between groups. These findings support the hypothesis that a simple modification of the skin incision may improve postoperative sensory outcomes and comfort after primary TKA without increasing surgical risk.
Study design
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- None (open label)
- Number of arms
- 2
- Model description
- This is a prospective, randomized, parallel-group study comparing a conventional midline incision with a modified J-shaped incision in patients undergoing primary total knee arthroplasty.
| Arm | Type | Receives |
|---|---|---|
| Midline Incision | Active comparator | Procedure: Conventional Midline IncisionParticipants undergo primary total knee arthroplasty using a conventional midline skin incision. |
| J-shaped Incision | Experimental | Procedure: J-shaped IncisionParticipants undergo primary total knee arthroplasty using a modified J-shaped skin incision, in which the distal portion of the incision is curved laterally at the level of the tibial tuberosity. |
Who may qualify
- Ages
- 56 to 81 years
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (5 listed)
- Adults undergoing primary total knee arthroplasty
- Diagnosis of Kellgren-Lawrence grade 4 varus knee osteoarthritis
- Planned treatment with primary total knee arthroplasty
- Ability to provide written informed consent
- Ability to comply with postoperative follow-up evaluations
Key exclusion criteria (10 listed)
- Valgus knee deformity
- Revision total knee arthroplasty
- Previous surgery on the affected knee
- History of periarticular fracture around the knee
- Pre-existing sensory deficit or neurologic disorder affecting the operative lower extremity
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| Conventional Midline IncisionAlso: Standard midline incisionA conventional midline skin incision is used during primary total knee arthroplasty. | Procedure or surgery | Midline Incision |
| J-shaped IncisionAlso: Modified J-shaped incisionA modified J-shaped skin incision is used during primary total knee arthroplasty, in which the distal portion of the incision is curved laterally at the level of the tibial tuberosity. | Procedure or surgery | J-shaped Incision |
Primary outcome
Area of peri-incisional sensory loss
Time frame: 2 months and 6 months postoperatively
The extent of peri-incisional sensory loss will be assessed using Semmes-Weinstein 10-g monofilament testing combined with a standardized grid-mapping method to quantify the area of numbness around the surgical incision.
10 secondary outcomes
Postoperative pain
Time frame: 2 months and 6 months postoperatively
Range of motion
Time frame: 2 months and 6 months postoperatively
Intraoperative Blood Loss
Time frame: Intraoperative period
Tourniquet Time
Time frame: Intraoperative period
Incision Length
Time frame: Intraoperative period
Wound complications
Time frame: Up to 6 months postoperatively
Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) Score
Time frame: 2 months and 6 months postoperatively
Knee injury and Osteoarthritis Outcome Score (KOOS)
Time frame: 2 months and 6 months postoperatively
Hospital for Special Surgery (HSS) Knee Score
Time frame: 2 months and 6 months postoperatively
Kujala Anterior Knee Pain Scale Score
Time frame: 2 months and 6 months postoperatively
Results and safety
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 29 May 2026.
- Background: PubMed 32072122James NF, Kumar AR, Wilke BK, Shi GG. Incidence of Encountering the Infrapatellar Nerve Branch of the Saphenous Nerve During a Midline Approach for Total Knee Arthroplasty. J Am Acad Orthop Surg Glob Res Rev. 2019 Dec 12;3(12):e19.00160. doi: 10.5435/JAAOSGlobal-D-19-00160. eCollection 2019 Dec.
- Background: PubMed 33786352MacDonald B, Kurdin A, Somerville L, Ross D, MacDonald S, Lanting B. The Effect of Sensory Deficit After Total Knee Arthroplasty on Patient Satisfaction and Kneeling Ability. Arthroplast Today. 2021 Jan 11;7:264-267.e2. doi: 10.1016/j.artd.2020.11.020. eCollection 2021 Feb.
- Derived from this study: PubMed 42360437Kahraman HC, Kilinc BE, Yavuz O, Erdem HF, Yilmaz B. The effect of J-shaped incision versus standard midline incision on numbness and pain in primary total knee arthroplasty: a prospective randomized controlled trial. Int Orthop. 2026 Jun 26. doi: 10.1007/s00264-026-06918-9. Online ahead of print.
- Individual participant dataSharing planned: No
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
The record lists no contact. Use the official record to reach the sponsor.
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing Conventional Midline Incision and J-shaped Incision in people with Osteoarthritis, Knee, run by Fatih Sultan Mehmet Training and Research Hospital at 1 site in Turkey (Türkiye).
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 5 inclusion and 10 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: finished, as of the sponsor's last update on 29 May 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in Turkey (Türkiye). Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Area of peri-incisional sensory loss (time frame: 2 months and 6 months postoperatively). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
On the ClinicalTrials.gov record for NCT07514598, which also lists 3 linked publications.
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 29 May 2026.